Method and means for treating metals



Feb.- 15 27.

M. w; ARRowooD METHOD AND MEANS FOR TREATING METALS Filed Aug. 8, 1921Patented Feb.'1j5, 1927.

UITED MILTON 'W. ABROWOOD, OF CHICAGO, ILLINOIS,

NEERING CORPORATION, OF WORCESTER,

mn'rnon AND means roa TREATING manna.-

' BEISSUED.

Application filed August a, 192 1. Serial in. 490,529.

This invention relates in general to a method and means for treatingmetals in furnaces, and while I have shown it in the present drawings asembodied in a melting furnace, it should be understood that theprinciples. thereof are capable of embodiment in furnaces used for otherpurposes, such as annealing or heating furnaces for instance.

In furnaces of this general character, and particularly in meltingfurnaces, it has been customary heretofore to provide a hearth which issloped to a depressed point where the tap hole is located. .As theresult of this shape of hearth, the solid charge of pig iron and scrapiron which is piledupon the bottom of the hearth for melting purposes,is concentrated over the depressed portion of the hearth where itassumes considerable depth, forming a barrier for the flame of burningfuel. It follows therefore that the flame cannot-penetrate toany'considerable distance into the base of the charge and becomesconcentrated to a large degree upon I and against the forward portion ofthe charge, while the remaining portions are subjected to very littleheat. The result is that the melting of the charge takes place veryslowly and requires the expenditure-10f a great amount of fuel.Furthermore, the molten metal forms a deep pool in the de pressedportion, the bottom" of which tends to become cooled so that inpractice, it becomes necessary to run the furnace for a considerableperiod after the metal is all melted before it is all heated,sufiiciently for pouring purposes.

(One of the primary purposes of my pres ent invention is to provide afurnace, the hearth of which will be substantially level from end to endand devoid of depressions :so as-to provide a relatively shallow bath ofsubstantially uniform depth. This construction permits of a more evendistribution of the'solid char e over the area of the hearth, with theresult that a large area of e the char e is exposed to the action of-the flames, thus materially facilitating and ex -melting. Manifestly,.the me a shallow bath having a large top surface" pediting the meltingof'thecharge and -re-- ducing the amount of fuel re uired 'for the tenmetal in exposed to the Heat in the" furnace canbe thoroughly heatedmuch. more expeditiously than the same q ap y of metal in a de p der.low pressure,

. 351,16 rice.

ASSIGNOR T0 GROUND- COAL ENGI- MASSACHUSETTS.

shallow bath furnace, the pouring may be begun soon after the actualmelting has been completed, thereby effecting a material economy both intime and in fuel.

To insure the flow of the molten metal from the hearth through the tapholes, the vhearth is preferably sh'ghtly inclined transversely eitherfrom one. side to the other, or preferably as herein shown, is slightlyarched transversely so that the molten metal will flow to both sidesthereof, where it may be withdrawn th-rough tap holes at each side ofthe furnace.

In furnaces of this character it has heretofore been customaryv tomaintain a strong draft from the melting chamber through the outletstack. by which a vast part of the heat units generated by fuel su pliedto the fur-- nace are carried away an dissipated.

invention contemplates. the delivery of t e fuelin a comminutedorpulverized form mixed ,with air, to the furnace In controlledproportions at' low velocity and unand .the ,communicating openingbetween the furnace and the stack is so located and so proportioned withrespect to the fuel pressure and the'size of the stack is soproportioned that the furnace chamber is usually maintained under aslight static pressure and the products of combustion leavethe chamberand are delivered from the stack at a low velocity. Instead therefore ofdrawing enormous quantities of heat up the stack, the fuel ispractically completely consumed in the furnace chamber so that its heatunits become effective 11 on the charge to 'be'heated or melted an aminimum of heat is 'lost through the stack, thereby greatly increasingthe efficiency of the furnace. andthe-draft openin between the furnaceand the stack are so esigned as'to favor a slight static pressure in thefurnace,'but by varying the fuel delivery pressure, this static pressuremay be changed to a substantially balanced draft or to an appreciableoutlet draft if desired. My invention therefore provides for a widerange of flexibility I The stack in its operation; to successfully meetalli-1,

ous con itions to which it may be sub-. jected. Y 4

Another feature of my invention resides in theprovision of means fordelivering t e cae m a e mi ed w h a to h furnace in a turbulentcondition, so that it- I swirls as amass of slow moving mixture over thesurface of the charge so as to more readily distribute itsheat thereto.The effectiveness of the burnlngmixture is further increasedby'delivering it downwardly or in' a downwardly inclined direction fromthe nozzle'u ainst 'the bath which results in a penetration of the flameinto the mass of loosely piled material forming the charge on thehearth, thereby causing the flame to continue along the hearth at thebase of the a charge while the charge is in solid state, and alsocausing it' to impinge against the adjacent margin of the bath whenmelted, thus producing a most effective heating action.

A further object of my invention is to provide a furnace in which thefront bridge wall is spaced a limited distance from the front wall ofthe furnace chamber, the forward end of the hearth between these wallsbeing provided with a masonry floor inclined downwardly from the frontwall to the bridge" wall so that any-slag deposited on this portion ofthe hearth will drain freely into the bath. In order however to relievethe bath from an accumulation of as much slag as.possible,'this floor isprovided adjacent the front wall and immediately beneath the point ofdelivery'of the fuel into the I furnace, with, a depressed pocket.

Since the fuel "is delivered at low velocity, the flame formation occurs"near the front .wall and that slag which results from the initial flameformation 'drops immediately into this pocket from which it may beremoved at intervals through cleaning doors communicatin structioneliminates to a large extent that rtion of the slag which isparticularly in- Jurious to thebrick work of the bath and therebymaterially reduces the cutting in words of the side walls of the furnaceat the sla line which has heretofore been it principa cause ofbrickrepairs. The'corrosive ac-' tion upon the brick walls is furtherreduced by the fact that the combustion in my improved furnace is rapidaud complete instead of progressiverthroughout the length of thefurnace, thereby causing an. improved gas condition within the furnacewhich-dimmishes the deteriorative effects upon the brick work andreduces the chemical; activity of the bath slag upon the furnace walls.

Another and important feature ofmy invention resides in the fact thatwhere the proportions of the several ingredients. of a charge aresubstantially correct, by mixing I I with thepulverized fuel just'suflicient'air to supportcom lete combustion, or, in other deliv-.

rovi ing a neutral flame; by eri g t is mixture at low velocity into'thefurnace so that the combustion isspeedy and complete; by directing theburning mixture downwardly-against the bath, and. by conwith the pocket.This 0011-,

trolling the pressure within the furnace, an extremely high, intense andpenetrating heat is produced, which quickly melts; the

charge without. burning out as large a percentage of the silicon andmanganese as has heretofore been burnt out with other methodsof firing.The result is that the furnace charge may contain a much largerpropontion of cheap scrap metal and acorrespondingly less amount of expensivepig iron than customary, thereby reducing [the cost of the charge whilestill producing malleable metal of the desired composition.

And it obviously follows as a corollary of the matter of the foregoingparagraph that.

regulation of the relative roportions of fuel and air admitted througthe burners will vary the character of the flame which may thereby bemodulated to meet the requirements of the charge. For instance, if theproportions of the carbon and silicon, manganese and sulphurconstituents be't'oo high, the proportion of air in relation to the fuelmay be increased toproduce an oxidizing flame, proportion of air areducing flame can be secured, while, as above, if the batch, isproperly proportioned as it should be,*a neutral flame is used whichwill neither reduce nor increase the relative charge ingredients.

Still another object of the invention is the proportions of the On theother hand,-by decreasing the.

provision of means wherebythe'direction of discharge of the fuelmixtfire into the furnace may be regulatedand controlled so that t maybe directed downwardly upon the masonry floor in front of the bridgewall, or

may be directed over the bridge wall into the forward end of the bath,or may bedi? rected toward a point in the bath more remote from itsfrontend, as desired, thus I providing for flexibility in the furnaceoperation so that it may be accommodated to various requirements andrendered highly Fig. 3' is \an-enlarged .sectional view through thedelivery end of the mixer burner.

. R v Referring now to the drawings more in detail, it will be observedthatmy improved furnace comprises an elongated chamber uninterruptedfrom end to end but comprising two portions, namely: the rear portion inwhich the ma-te ialvtc be heated. is p tial combustion of thevfuel.begins and'is sidered as a combustion chamber.

nace chamber asa whole comprises the front.

practically completed and which-maywbe (fxlilne rwall 5, rear wall 6,and the roof 7, allof which are constructed of fire brick in a wellknown or preferred manner and bound towith buck stays 9.

' its ends as has-hereto ore been customary.

gether by suitable tie rods 8 cooperating The bottom of the chamber isprovided with a bridge wall 11 extending upwardly into the chamber alimited distance, this bridge well being spaced a limited distance fromthe front wall and the space between these walls being filled in andprovided with a masonry floor 12 which is inclined downwardly from itsfront edge to the top of the bridge wall. The foundation 13 of thefurnace disposed rearwardly of this bridge wall may be of suitableconstruction suitably covered in 'annealing or other heating furnaces,but for melting furnaces, such as I have herein illustrated, thisfoundation is covered by a sand bed 14 forming the hearth which .issubstantially level from end to end instead of having a dee depressionbetween This bed is adapted to accommodate a bath 15 of molten metalwhich is relatively shal-- low and of substantially equal depth from endto end, although in practice the rear portion is slightly sloped fromrear to front for a considerable distance to facilitate flow of metal tothe tap openings and to-decrease the depth of the bath toward the rearofthe furnace where the heat 'islemhigh. This substantially level hearthermits a substantially even distribution o the solid charge over thearea of'the hearth andconsequently the melting flame, instead ofencountering a deep barrier to the bottom of which it would nets ofcombustion down in be unable to penetrate, is caumd to impinge against alarge area'and to penetrate the charge offloose piled solid material andswirl along the. p to most efiectively deliver its heat units to thecharge and reduce the melting time to a minimum. In practice thematerial will be piled somewhat higher at the front end of the ile thanit is in the rear of the chamber so t 'at a larger quantity will besubjected to the maximum heat near the forward end of the hearth. Thedecrease in. depth of the bath toward the rear end correspondsapproximately to the decrease in temperature and pressure of theproducts of combustion as they approach the rear end of the chamber.Because of the reduced scaleof the drawings, this decrease of bath depthis scarcely apparent in Fig. 1-. I .For the purpose of holding the hotrodthe ath,

ttom of the charge so ,as,

rearend, and furthermore, the outlet open-" ing from the furnace to thestack and also the top of therear bridge wall are dis osed 'onlyslightly above the level. of'the ath. The entire structure therefore, isconducivevto the .most complete transference of heat 14 thereof ispreferably slightl convex in apparent transversecross section, as willfrom Fig. 2. This upward arching of the floor is adapted to cause themetal to flow Y to the sides of the bath from which it may be drawnofithrou h one'or more tap Holes 16 located at eac side; of the. furnace.

Should it be preferable todraw the entire charge from one-side of thefurnace, the bath floor, instead of being transversely arched,

maybe-slightly inclined from one side to the other so as to deliver themolten metal to one side of. the furnace.

The furnace may be charged through doors or openings formed in the sidewall or through t e roof, which may be equipped with removable beings,as is customary in reverberatory furnaces. In this instance, I haveshown for purposes of illustration, the side wall provided with aplurality etcharging doors 18, such as are" customarily emplo ed inopenhearth furnaces and through which the pig and scrap iron andother'inredients of the charge ma beintroduced into the chamber anddistributed over the hearth. I y

It will be observed from Fig. 1 that the level of the bath is below thetop of the masonry floor 12 and the u per edge of the bridges wall, sothat any s ag. which is death will drain freely into the bath. Adjacentthe front wall hithe floor 12 .is provided with a pocket 19 disposedimmediate] beneath the delivery openings 21 through which the groundcoal mixed with air is delivered into the furnace. being-delivered atlow velocity, the ignition begins immediately upon its entrance into thefurnace, and sincea large proportion of the sla I formed, andparticularly that portion wiich is most injurious to the brick Work ofthe furnace is produced at the point of flame formation, it will beapparent that this slag willdrop directly into the pocket 19 where it iscollected and precluded from entering'the bath. I have found that the searatlon of the slag produced atthe point 0 flame formation of the fuelmixture, and

theelimination of this ortion from the bath 3 The mixture ismaterially-reduced, thereby'diminlshing corrosionof the brick workatthef slag line the necessity for repairs to the furnace. The

- slag collected in the pocket 19-may be cleaned out at intervals throuh cleaning doors 22 located in the side wa, ls of the furnace at eachend of the pocket.

I have shown in the present installation somewhat diagrammatically, apreferred the referred specific construction in. my co- 5 type of burnermixer, the general construction of which is disclosed in U. S. PatentNo. 1,355,444, granted October 12, 1920, and

a ing application, Serial -No. 299,833, led May 26,1919, now Patent No.1,474,613.

-In this t pe of burner,'the powdered coal is deliver from a hopper 23through a worm screw easing into a mixing'cylinder 25 to which air.under pressure is delivered through a sup y pipe 26. The fuel underpressure *mixe with air is then conducted through a connection 27 to themixer proper 28 to which additional air under pressure is suppliedthrough a ipe 29. After being 'thoroughly'mixed with air in. this mixer,the

fuel'is delivered through a tapered down-' wardly inclined conduit 31into the forward end of the furnace chamber. The sha of this conduitcauses the mixture of fue and air to be delivered'in a turbulent,swirling condition and since the mixer is of the low velocity type,'this turbulent suppl of.fuel continues after ignition in a swir ng massthrough the furnace in a condition which is most favorable --to.thetransference of it heat'to the charge in the furnace. r

; It will benoted that the delivery of the combustible mixture is in adownwardly'oblique direction, but the vertical direction-of which mayhandle 35 or other means by which the posi-.

discharge may be varied and controlled by' means of a controlling plateor damper 32 1 located'in the nozzle 33 of the burner. This controllingplate, which inay be made of sheet iron or suitable material, ispivotally supported u on a-t ransve rse bearin rod 34 equ pped atone onwith a tion of the plate may be adjusted to any point intermediate the.full open position shown. in full lines in Fig. 3- and the full "closedposition shownin dotted lines in said figure. Any intermediatepositionbetween the two itions shown will va the direction" of dischar eof the combusti le mixture so that'it may e diverted downwardly upon thefloor 12 or over the edge of the bridge wall into-the bath or into thebath at'a point more remote from the bridge wall depending on theposition of the coursefadjusted to meet e requirements of the charge andthe condition underwhich the furnace is being used. Forpurposes of gggsiens tot operatively the holding the late-1n any adjusted position, Ihave provi ed a sector member .36 having in view, the top wall of thechamber may zbe depressed, as indicated at, .37, directl extending supp]plate which is, of. 't

. su.r e is normally maintainedin the. furn ce handle 35 to hold it inany adjusted position.

While one or a series ofburners for supplying fuel to the furnace may beemployed, depending on the size ofthe furnace and-the size of theburners, I have shown in the present instance, as will be apparent fromFig. 2,

.two. burners having the1r. deliverynozzles spaced relation in the.front 33 located in 'wal15.

The manipulation of the plate '32willinmost instances be sufiicienttocause the delivery of the fuel at the requisite point in the bath, andthe sloping top wall 7, to ether I with the location and size of theoutlet opening and the proper proportion of the stack and'properregulation of the .fuel pressure causes the flame-to hug the bathclosely throughout its length to most eflectively heat the bath. In someinstances, however, it may be preferable to employ a top blast toaugment the downward-deliverylof the flame and I have therefore madeprovision in'my improvement for the employment of such a blast whenrequired. With this end above or just rearwardly of the'bridge we I- 11and this depressedpo'rtion is e nipped with a plurality of downwardlyirected blast nozzles 37 through which air under pressure is deliveredfrom the transversely stated the top b astmay be 'if desired, but I havefound that with my method, the

and a high degree of efiiciency is obtained without the employme t ofthis blast,- which has heretofore been considered indispensable.

The rear end of the furnace chamber connected with a properlyconstructed stack 39 throu h which the products of combustion areiscliargedand communication is es- .tablished between the chamber andthis stack 'r'eferably ridge wall 41 through an opening 42 which .isproportioned according to'size of the furlost for effective use. Byemployin a low pressure at, the fuel delivery nozz es," the velocity ofthe flame through the furnace'is reduced so that its heat units mabetrans ferred tothe char e.-'- This'desira 1e effect is furtherincreased V y p'rop'ortioning the connecting. o ening 44 tothe stack andpropertionln'g t estack itself so. that a static prespipe 38. Aspreviously flame is sufficiently controlled and depressed 9 immediatelyabove the rear nace and delivered to the stack so as to 'be chamber.This pressure as distinguished burned fuel articles are wasted throughthe 1 been maintained in these furnaces, greatly facilitates thetransference of the heat units from the burning mixture to the chargeand insures a practically complete combustion.

of the fuel particles before they leave the chamber, with the resultthat few, if any, un-

stack. Obviously, this feature greatly en'- hances the efliciency of thefurnace. By regulation of the feed pressure, this static pressure maybecontrolled and may be reduced to a balanced draft or even to anappreciable u draft if desired.

It will be 0 vious from the foregoing that in my. improved method, thepulverized fuel thoroughly mixed with sufficient air to support completecombustion, is delivered in a turbulent,- swirling condition into thefurnace in an obliquely downward direction and at low velocity so thatignition and combustion take place close to the delivery nozzle. Thecombustion being speedy results in an intensive heat quickly liberatingthe gases so that they do not long remain in anascent condition in whichthey would readily com-' bine with the bath slag and increase itscorrosive effect upon the furnace walls. Furthermore, a considerableproportion of-the sla resulting from flame formation is imme iatelydeposited in the front pocket beneath the burner so that it does notmingle with the bath slag, and consequently, not only the quantity ofbath slag is reduced, but

the character of the slag is materially improved. The flame directedagainstthe bath eing in a turbulent and swirling condition tends, byreason of its point and direction of delivery into the bath, and byreason of the flat character of 'the bath floor, to penetrate the chargeof loosely piled solid material upon the hearth and to travel along thehearth beneath the charge so as toexpedite the melting of the same. Whenthecharge is melted, the flame impinges upon its surface and because ofthe fact that the bath is shallow, and of substantially uniform depth,it becomes quickly and uniformly heated and reduced to a conditionsuitable for pouring without prolonged operation of the furnace, as isrequired. where the bath floor is deeply depressed so that the moltenmetal accumulates in a deep pool. The rapidity of the heating in thefurnace is further augmented by the fact that the flame is caused toclosely hug the bath throughout its length. This condition is producednot only by the direction, velocity and manner of the fuel delivery intothe furnace, but also by the fact that the rear portion of the furnacechamber in which the products of combustion are coolest is ofrogressively reduced cross sectional area y reason of the downwardlysloping roof, and furthermore by the fact plete combustion and the mosteflective transference of heat to the charge. My method contemplates thedelivery with the pulverized fuel itself of sufiicient air to supportcomplete combustion. Consequently, an auxiliary supply of combustion airthrough the walls of the furnace is unnecessary, and in fact, thedelivery of auxiliary cold air into the furnace is not desirable sinceit tends to reduce the temperature thereof. The top blast may thereforebe and preferably is entirely eliminated, but since'some types of workseem to be slightly more efiectively performed b additionally depressingthe flame throug the instrumentality of a top blast, I have illustratedthe application of a top blast to the furnace. herein shown.

By the practice of the method above disclosed, l am not only able toreduce the fuel consumption and to expedite the melting, heating andpouring of the charge, but-also to em loy in the composition of thecharge a cons'i erably greater proportion of scrap iron than hasheretofore been possible in-the production of metal of a predeterminedcharacter and composition. This feature is manifestly of significantimportance since the proportion of pig iron required may be diminished,thereby decreasing the cost of the furnace charge. In practice, I havefound that with my novel method,.l am able to utilize, instead of over60%-expensive pig iron, high in silicon and manganese to 40% of scrapwhich is low in silicon and manganese, as has heretofore been customary,considerably more scra than pig iron in a charge, and still iron ofsuperior quality containing the requisite predetermined proportions ofsilicon, manganese, carbon and sulphur manganese. Should a test of themolten metal show it to be too low in one ingredient, the flame may beregulated to hold the molten mass in status quo with respect to theother ingredi ents while the requisite quantity of the low ingredientisutddedto the charge to-produce the desired analysis. My inventiontherefore, affords a wide range of flexibility in its operationand theresults which may be secured thereby. I

Furthermoraby reason of the elimination from thebath of a portion of theslag and by improving the character of the bath slag,

as the result of improved gas conditions in diminished, as well asrendering the furnace serviceable for prolonged periods of time.

obtain a resultant malleable hearth bein mixture I .is believed thatmyinvention, and many of its inherent advanta es, will be underhe stoodand appreciated mm the foregoing.

without further description, and while have shown and described apreferred method and means for carrying it into effect,

obviously, both the method and a paratus ma be varied within considerablimits wit out departin from-the scope of the invention as define in thefollowing claims.

- I claim 1. In afurnace, the combination of a heat-jing chamberprovided with a hearth, said substantially level-from end to end, are edslightly upwardly in cross section and ads ted to contain a shallowbath,- and means or delivering a combustible of comminuted fuel and airto said chamber.

2. In a furnace, the combination of a heatin chamber, comprisinga-hearth substantia 1y level from end to end 'providinga relativelyshallow bath, an outlet stack com- 7 a'shallow bath, an out et stack,and arear wall between said chamber and stackprovided with a restrictedopenin' adapted to.

maintain a static pressure m-sai chamber. 4. A furnace, comprismg achamber havin I front and rear'walls, a hearth, a bridge we 1 spacedfrom said front wall, a floor in-' clined upwardly from said bridge walltoward said front wall and provided adjacent I the front wall with apocket, and means for delivering a mixture of air andico'mmin-ut ed fuelto said chamber directly over said pocket.

5 '5. In a furnace, the combination with a chamber provided with ahearth and a floor ture of comminutedfuel and air, means 'for slopingupwardly and forwardly of said of means for delivering to said chamberat low velocity-a mixture of comminuted hearth fuel and air in aturbulent condition, and a pocket-in said floor immediately beneath the.point of entrance'of the mixture into the chamber .adapted to receivethe'slag duced at the point -of flame. formation in said mixture. 1 a

6. In a furnace, the combination of a a chamber comprising front'andrear walls, a-

hearth, means-for maintaining a static'pressure 1n the chambeameans forad lying to said chamber. in turbulent condition a mixvarying thedirection of 'dischar of said nuxture into said chamber, and a 1 pocketdisposed adjacent to and beneath e point insaid.

'of entrance of said mixture into the chainconsists in delivering to afurnace containing a charge of material to be treated, a supply ofpulverized fuel thoroughly mixed with 'suflicient air to supportcomplete combustion, causing the delivery of such vfuel in a-turbulentcondition and in a downwardly inclined direction, separating a portionof' r. a 7. The herein described method, wliiolr the slag resulting from.flame formation and collecting the same at' a point remote fromthe'bath. causing the flame to hug the bath, and maintaining a staticpressure in the heating chamber of the furnace.

q 8. The herein described method, which consists in delivering inturbulent condition to a chamber containing a char e of material'to betreated, a supply 0 pulverized combustible material atlofw velocitythoroughly' mixed with suflicient air to support combustion, causing theflame from said 7 combustible material to travel in proximity -'to thebottom of the charge, and regulating the pressure within said chamber.

9. The herein described method !'which' I consists in producing amalleable metal of redetermined composition by charging a urnace withpig iron and scrap, the quantity of scrap being in excess of the pigiron, and reduc' the charge to malleable iron of. .a predetermlnedcomposition by subjecting the charge to a flame of such quality andintensity aswill reduce the charge without losing an appreciable portionof the silicon andmanganese contained in. the charge.--

. 10. The method which consists in deposit-= of less than 50% pig ironand more than 50% sent iron and subjecting said'charge in a furnace acharge of metal consisting to the action of a flame of such qualitandintensity as will reduce the charge without 1 a preciable loss-ofsilicon and manganese iron.

' 11. The method hf treating metals which consists in'subjecting acharge of metal in a.

furnace to the action of a burning turbulent mixture of pulverizedfueland air delivered at low velocity, and controlling the relativeproportions offue'l and air so as to roduce a flamewhich will have thedesire effect 1. upon the charge.

12. The method. of'treating metals, wh chconsists in subjecting a chargeof metal in a furnace to the action of a burningturbnlentmixture ofpulverized fuel and air delivered ereby producing a high grade malleableat low velocity, and controlling the quantity and'relative proportionsof fuel and-air so as to produce a flame which will have the desiredeffect upon the char 13. The method'of metals, which consists j in subjting a char a to the action of a irnin turbulent mixture of .ptlverizedfuel an de- .qfgmetaLinn livered at low velocity, regulating therelative proportions of fuel and air and maintaining a static pressurein the furnace.

14.. The method of treating metals, which consists in subjecting acharge of metal in a furnace to the action of. a burning turbulentmixture of pulverized fuel and air,'and regulating the. static pressurein the furnace.

15. The method of treating metals,'which consists in subjecting a chargeof metal in a furnace to the action of a burning turbulent mixture ofpulverized fuel and air, and regulating the proportions of fuel and airto thereby produce an oxidizing, a reducing or a neutral flame at will.

16. The method of treating metals, which in the metal when poured oftherequisito proportions of carbon, silicon, manganese and sul hur.

17. T e method-of treating metals, which i consists in subjecting a chare of metal in a furnace to -the action of a urning turbulent mixture ofpulverized fuel and air, and regulating the flame to cause theproduction of the requisite proportions of the various ingredients inthe finished batch.

MILTON W. AnRoWooD.

